client stuck on mcs1

Hello all,

I’ve deployed Cambium epmp1000 4 sectors GPS antenna in highly crowded environment. My clients UL/DL RSI is around -65dbm. UL/DL NR is 36 and 52 but almost all of my client MCS rate is 1 due to which I my clients are getting 20-30% packet loss. Any idea why I am getting low mcs rate?


Can you give more detail in your setup? What software are you running on both the APs and the Stations? You mention 4 sector setup, how close are each APs on the tower? What frequencies are you running at?

On the client side with MCS1 were you able to run the Spectrum Analyzer for a few minutes? What were the results.


Fundamentally, your problem is 90% likely due to interference on the channel you are on. It is very important to do a spectrum analyzer and see what your interference level is on the channel you are on. The SNR reported on the radio is just a relative number compared to a non WiFi noise floor of 95. In order to see your real interference level, run the spectrum analysis and then subtract the RSSI from this interference level. For MCS1 to operate the difference needs to be about 8dB. I suspect you are real close to this 8dB and even with that you are seeing packet errors. I would highly recommend moving to a different channel that is cleaner. Last but not least, are you in the US? If not, you should upgrade to our 1.4.1 SW release where you will have more power. This will help you with getting out of MCS1

Hey Corey,

I have had similar results on some channels at a new ePMP site. After running the spectrum analyzer, and finding a clean channel source, I connected a client and the client stays at MCS1. It will only go up for a brief second but then go back down.

What is really confusing is now I have it on a channel where there is a 5mhz overlap with a near by AP on a tower about 500 feet away and the client is hovering between MCS13-15. They are using UBNT gear on the near by tower.

I am running firmware 1.4.4. US model @ 23dbm.

Jason - You may want try our beta release found here:

in it are rate adapt improvements which will give you higher throughput in the presence of interference.

Much better in version 2.0 than before. I am seeing the clients all sit at mcs13 to mcs15. Only problem I still see is their upload msc rate still bounces all over the place. One second it will be mcs13 then the next it is mcs1. Internal speed tests will show 70mbps down and 2 up. Clients are also using 2.0. (All the final release, non beta)

I checked and it is a clean channel as well as ran the new interference check on the AP and client. Nothing came up. All AP’s are GPS sync.

Let me know if you have any ideas. I thought about spacing the AP’s more vertically on the tower from each other.

Jason, If the MCS is jumping up and down, there has to be intermittent interference. Try two things:
1. Run eDetect under Tools menu. Run it for about 60 seconds and see if it reveals any interferers on channel.
2. Run the Spectrum Analyzer on the AP but this time, let it run for a few minutes and look for what you see on the peaks on your channel. Intermittent interference will hopefully be seen on the peak readings on the SA.

If you still have issues, please give our support guys a call through here: